For example, a mobile phone employs a waterproof structure in which a waterproof packing is interposed between two cabinets which constitute a casing and compressed by the cabinets to seal the inside of the casing.
However, a portable electronic device having a conventional waterproof structure is required to include an additional component such as a waterproof packing.
In view of the above, an object of the present invention is to achieve effective waterproofing with a simple configuration in a portable electronic device which has a water entry portion, such as a terminal portion, located on an upper part of a casing.